Maliau pitfall project (proposal)

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Recently in Borneo there has been controversy surrounding land use of secondary forest. Specifically, there is a debate over whether secondary forest should be used for oil palm plantations or whether it is worth preserve or harvesting sustainably to because of its biodiversity. Much of this argument hinges on the species diversity of these secondary forests relative to primary forests.

Although this information is key to settling this debate, the species richness and composition of secondary forests compared primary forests is not fully understood. Recent research has suggested that secondary forest may be an important for large animals. For instance, Mark Ancrenaz, orangutan expert believes that orangutans may actually more successful in secondary forests due to the greater number of fruiting trees in secondary forests (lecture by Mark Ancrenaz). Although it is becoming clear that secondary forests may well support mammalian life, arthropod composition and richness in secondary forests relative to primary forests remains unclear.

One study conducted in Costa Rica found that arthropod assemblages in epiphyte mats “were thinner and less structurally diverse in secondary forest” (Yanoviak et al., 2007). Another study that looked at arthropod canopy communities tropical montane landscape in the neotroprics and found that there was no difference in species richness between secondary and primary canopy arthropod communities. However, they did find a lower density of arthropods in secondary forests (Schonberg, 2004). Another study conducted on moths in Mount Kinabalu National Park found that there was no distinguishable difference between moth species composition of disturbed primary, old-growth primary, and undisturbed primary forest (Fiedler et al., 2004). All of these studies present conflicting information on the effect of forest stage on arthropod communities, whether they are terrestrial or aerial. Comparing the terrestrial arthropod communities of secondary and primary (forest and gap) forests in Maliau would help clarify the uncertain effects of secondary and primary forests on arthropod composition and richness.


  • What is the difference in richness and composition of terrestrial arthropods in closed forest and gap environments of primary and secondary forest?


  • Terrestrial arthropod richness and composition will vary significantly between location.

Closed canopy primary forest patch will have the highest terrestrial arthropod richness and composition, followed by gap primary forest patch, closed canopy forest patch, and gap secondary forest patch.

We based our hypothesis on the follow research:

  • Logged forests have considerable open areas that allow the litter to be exposed to sunshine, which reduces the rate of litter decomposition. On the other hand, closed canopy litter is more humid and decomposition proceeds at a much faster rate. Because many insects live in decomposing litter, dry litter in open forest patch will attract fewer insects (Iskandar, 2004).
  • Canopy gaps have the lowest mite density and diversity, and are more sensitive than closed canopy to year to year changes in climate (Marra and Edmonds, 2005). This sensitivity of the gap could lead to the more arthropod extinction in gaps and therefore lower diversity.
  • More disturbances decrease arthropod morphospecies richness and the number of unique species in all forest types (Goehrig et al., 2002).


We will sample arthropods in primary forest near the Maliau River in the Maliau Basin and secondary forest with twelve years of growth after logging close to the Maliau Basin Research Centre. Pitfall traps will be set to measure terrestrial arthropod presence in closed forest and gap environments in each forest type. Three plastic cups half-filled with detergent water and covered with cardboard rain awnings will be arranged in an equilateral triangle for each trap, with three trap triangles per location. Traps will be paired by gap and forest to minimize other factors (ex. Soil type, elevation), and pair locations will be determined by randomly selecting gaps and conducting random walks to determine the forest location. The pitfalls will be set out each morning for 24 hours each, with different locations sampled each of the three days. The arthropod contents of each trap triangle will be identified down to order specificity using microscopes, and the composition and order richness will be compared between primary forest, primary gap, secondary forest, and secondary gap. We will conduct an analysis of variance on the arthropod samples and check for correlations between any of the locations.